We could also potentially list a hidden service address as a WebRTC ICE endpoint, though we would need to be careful about this since it means that potentially every Tor Browser user who visits a WebRTC-enabled page would suddenly spin up a hidden service. I wonder if we can have Tor create the keys for a hidden service without actually starting it up unless it is actually negotiated by WebRTC.

This suggestion actually came from wiretapped. WebRTC is no longer just for making calls. Tons of crazy decentralized apps are being built on top of it. Ex: ​https://instant.io/